“ The potential is very great — to use the eye to diagnose what’s going on elsewhere in the body, particularly in the brain. ” — ALISTAIR BARBER, PAGE 11

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Life’s buildingblocks can growclose to homeComplex organic chemicalsmay be common near starsSTORY ONE

By Nadia Drake

Though life is a complicated brew, some of its ingredients can be plucked from Earth’s backyard instead of being imported from
more distant interstellar fields.

In a new study, scientists suggest that
complex organic molecules — such as the
amino acids that build proteins and the
ringed bases that form nucleic acids —
grow on the icy dust grains that lived
in the infant solar system. All it takes
are high-energy ultraviolet photons to
provoke the rearrangement of chemical
elements in the grains’ frozen sheaths.

If making these organic ingredients
happens this readily, then exoplanetary
systems are probably seeded with the
same fertile, organic pastures. “Anywhere
you have ice and high-energy ultraviolet
radiation, this process is going to take
place. And those are both pretty common in the universe,” says planetary scientist Dante Lauretta of the University
of Arizona.

In the new work, reported online
March 29 in Science, researchers simulated the young solar nebula, a swirling
disk of gas and dust that surrounded the
sun until planets began forming, about
4.5 billion years ago. Over a 1-million-year
period, the team tracked the individual

The dusty disk surrounding the young star NGC 1333-IRAS 4B (illustrated) prob-ably contains complex organic molecules formed on icy grains, a new simulationshows. Such molecules could provide the building blocks of life for many planets.

movements of 5,000 dust grains, tiny
organic-toting particles covered in ices
made from compounds such as water,
carbon dioxide, methanol and ammonia.

“ We wanted to know exactly what con-ditions those ice particles were seeing,”says coauthor Fred Ciesla, a planetaryscientist at the University of Chicago.“It’s a turbulent environment, and everyparticle follows its own path.”Grains lofted above the disk’s planemet warmer temperatures and high-energy ultraviolet photons — the cata-lysts needed to convert elements in thesimple ices to more complex molecules.In these types of reactions, photons strik-ing chemical bonds create what studycoauthor Scott Sandford calls “unhappyradicals and ions”—species that arehighly reactive and ready to recombine.As warming temperatures cause the icesto evaporate, those elements can findpartners and form new molecules.